油藏原油微生物降解的氮同位素分馏效应

选取辽河油田冷东地区来自Es3烃源岩不同性质原油,测定氮同位素比值,试图分析生物降解过程中原油氮同位素的分馏作用,探讨含氮化合物组成的变化机理。正常原油与相应干酪根的氮同位素比值接近,δ15N分布在4.0‰左右。遭受生物降解的原油,氮同位素比值明显增加,δ15N接近或超过10.0‰。比较遭受不同程度微生物降解自然系列的原油,氮同位素比值的变化与降解程度相联系。微生物降解过程中发生氮同位素分馏作用这一事实暗示降解原油中含氮有机化合物在降解过程中参与了代谢。

Nitrogen Isotopic Fractionation of Crude Oil during Biodegradation

Nitrogen isotopic ratio of several oils with different physical and chemical qualities from Lengdong zone in Liaohe oil field is analyzed to understand the mechanism of nitrogen isotopic fractionation and the metabolism of nitrogen bearing compounds during biodegradation in this paper. The δ 15 N of normal oil is about 4.0‰ approaching to that of the kerogen whereas the δ 15 N of biodegraded oil increases obviously with the value close to or over 10.0‰. Moreover, the δ 15 N vary with the degree of degradation. The fact that nitrogen isotopic fractionation has occurred during the oil biodegradation suggests that nitrogen bearing organic compounds in oils be involved in the metabolism of bacteria.